Risk factors for stroke should be used to determine whether anti-clotting therapy is given to people with an irregular heartbeat called atrial fibrillation (AF), according to revised Guidelines for the Management of Patients with Atrial Fibrillation released today by the American College of Cardiology, American Heart Association and the European Society of Cardiology.

Atrial fibrillation (AF) is the most common heart rhythm disturbance and it increases the risk for stroke, heart failure and all causes of death, especially in women. Presently AF affects more than 2 million Americans and 4.5 million Europeans, according to the joint statement. The number of patients with atrial fibrillation is expected to increase even more due to an aging population, a rising number of people with chronic heart disease and improved diagnostic possibilities.

During AF, the heart’s two upper chambers (the atria) quiver instead of beating effectively. Blood isn’t pumped completely out of them, so it may pool and clot. If a piece of a blood clot in the atria leaves the heart and lodges in an artery in the brain, a stroke results. Moreover, when the very rapid electrical signals from the atria reach the lower chambers of the heart (the ventricles) they start to beat quickly and irregularly causing palpitations and decreased blood pumping leading to tiredness and breathlessness.

Previous guidelines published in 2001 recommended using several patient characteristics – age, gender, heart disease risk and concurrent conditions – to decide proper anti-clotting therapy for these patients. The new approach recommends that the risk for stroke should be the main factor, said Valentin Fuster, M.D., Ph.D., co-chair of the guidelines writing committee, fellow of all three associations, and professor of medicine and director of the Mount Sinai Cardiovascular Institute in New York.

“We focused on stroke risk because AF is associated with increased long-term risk for stroke,” he said. “About 15 percent to 20 percent of strokes occur in people with AF, and those strokes are especially large and disabling.

“Incorporating existing recommendations on anti-clotting therapy from the stroke primary prevention guidelines will streamline patient care and make recommendations clearer for physicians,” he said.

In the United States and Europe, hospital admissions for AF have increased by 66 percent during the last 20 years. It is also expensive, with total costs approaching €13.5 billion (about U.S. $15.7 billion) in the European Union alone, according to the statement. No figures are available for total U.S. costs.

The revised guidelines also recommend daily aspirin therapy (81–325 mg) to guard against blood clots in AF patients with no stroke risk factors. Aspirin or warfarin is recommended for those with one “moderate” risk factor (over age 75, high blood pressure, heart failure, impaired left ventricular systolic function or diabetes). Warfarin is recommended for people with any “high” risk factor (previous stroke, transient ischemic attack [TIA], systematic embolism or prosthetic heart valve) or more than one moderate risk factor.

According to co-chair Lars E. Rydén, M.D., Ph.D., also a fellow of all associations and professor emeritus at Karolinska Institutet in Stockholm, Sweden, the guidelines help physicians prioritize the objectives of patient care according to the following steps: 1) controlling heart rate, 2) preventing clots, and, if possible, 3) correcting the rhythm disturbance. Rate control usually involves achieving a ventricular rate (pulse) of 60 to 80 beats per minute at rest and between 90 and 115 beats per minute during moderate exercise.

Also new in the guidelines, catheter ablation — a procedure that corrects irregular heartbeat with radiofrequency energy — is considered “a reasonable alternative to drug therapy to treat AF in patients with little or no left atrial enlargement, and in whom drug treatments did not stop the rhythm disturbance,” Fuster said.

Depending on symptoms, controlling the heart rate may be the reasonable therapy in elderly patients with persistent AF who have hypertension or heart disease, according to the joint statement.

For people under age 70, especially those with recurrent AF and no evidence of underlying heart disease, rhythm control may be the preferred approach, starting with drugs and by means of catheter ablation if medication fails to stop the attacks. Both Fuster and Rydén emphasized that “Regardless of the approach, the need for anti-clotting therapy should still be based on stroke risk and not on whether proper heart rhythm is maintained.”

The European Heart Rhythm Association and the Heart Rhythm Society collaborated on the statement.

The executive summary of the guidelines is available online here and will be published in issues of Circulation: Journal of the American Heart Association and Journal of the American College of Cardiology.